How do I switch from AM/PM to 24H?

Every date field in Zooper Widget is completely customizable. If you want to switch from AM/PM to 24H, just press "Layout", select the module containing the piece you need to change, press "Edit Text" and replace KK with HH in the #D..# pattern. You can also use "TT" if you want to use the current default according to the phone settings.

If you want more info on date field formatting, please check the date reference page.